Patent GB-477007-A (GB)
Title: Improvements in or relating to electric circuit breakers
IPC: H01H33/32
Filed: 1936-06-18
Abstract: 477,007. Pneumatic actuation of switches ; liquid-blast switches. FLURSCHEIM, C. H., and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. June 18, 1936, No. 17007. [Class 38 (v)] [Also in Group XXIX] The opening of a high-voltage circuitbreaker is effected or at least initiated and in the case of an oil-blast breaker the oil-pump piston is also actuated, by an air-piston and cylinder to which the compressed air from a reservoir or supply is admitted through a servo-type air-valve, the auxiliary valve of which is adapted to be tripped by a high-speed trip magnet of the flux-diversion type. The invention can be employed in the arrangements described in Specifications 477,005 and 477,006. In Fig. 1, the actuating piston 1 operates the contacts through a connecting rod 2, and works in a cylinder 3 connectible with the air supply over a pipe 4 and servo valve 5 normally retained on its seating by a light spring 8. The casing 6 above the valve 5 and its piston 9 is in communication with pipe 4 by a small byepass 10, The auxiliary mushroom valve 11 is held closed by a spring 12, opening of which releases the pressure admitted by 10 behind the piston 9, so that the latter is suddenly lifted to open valve 5 and admit air to depress piston 1. A lever 16 pivoted at 17 is normally held by its armature 19 being attracted to the flux-diversion magnet 20 against the action of a spring 18, the torque of which overcomes the compression of spring 12 and the air-pressure on the valve 11. In order to restore the lever 16 to its attracted position after release, either a cam 21 actuated by the contact-operating mechanism lifts a rod 23 to engage the lever 16, or the latter is lifted by a plunger 25 in a cylinder 26 which communicates with cylinder 3 by a pipe 28 and port 29 which is uncovered by the piston 1. A further port 30 leads over pipe 13 to the exhaust from valve 11, which port, when uncovered by piston 1, passes compressed air to the rear side of piston 9 in order to close the valve 5 (ready for reclosure of the breaker) at a higher speed than byepass 10 allows. A further port lower down the cylinder 3 exhausts the air from behind piston 1 immediately after valve 5 has been closed. In the application to a circuit-breaker generally arranged as in Specifications 435,143, 435,419, and 441,734, in which movable contacts are arranged at the remote ends of the device, or a single movable contact only is provided at one end, the byepass 10 is arranged in valve 5 itself and the latter is, as shown in Fig. 2, arranged differently. The rod 2 of piston 1 is connected to a floating beam 43, to which is pivoted at 51 a link 52 connected to the piston 53 of the closing cylinder 54. Air from source 55 is admitted to the latter over pipe 56 by means of a valve 57 tripped by the closing trip magnet 58 through mechanism 59. One end of the beam 43 is pivoted to a lever 44 on a shaft 45 which operates the blast piston and is provided with a reset spring 50. The operating shafts 37, 62 of the respective movable contacts (where two are employed) are interconnected by levers 63, 65 and link 64, and shaft 62 is also connected by link 60 and lever 61, which carries the valveresetting cam 21, to the end of beam 43. A further lever (not shown) on shaft 62 operates a dashpot arrangement for effecting a pause in the contact-separation after an initial opening movement, while the arc is being quenched. The lever 65 is pivoted to a powerful toggle spring 66 which is pivoted at 67 and controls the contact-movement after initial positive separation by the piston 1.